Effects of Metabolic Syndrome on Semen Quality and Circulating Sex Hormones: A Systematic Review and Meta-Analysis

Abstract

Previous studies were controversial in the effects of metabolic syndrome (MetS) on semen quality and circulating sex hormones, and thus we conducted a systematic review and meta-analysis to clarify the association. A systematic search was conducted in public databases to identify all relevant studies, and study-specific standardized mean differences (SMD) and 95% confidence intervals (CI) were pooled using a random-effects model. Finally, 11 studies were identified with a total of 1,731 MetS cases and 11,740 controls. Compared with the controls, MetS cases had a statistically significant decrease of sperm total count (SMD: −0.96, 95% CI: −1.58 to −0.31), sperm concentration (SMD: −1.13, 95% CI: −1.85 to −0.41), sperm normal morphology (SMD: −0.61, 95% CI: −1.01 to −0.21), sperm progressive motility (SMD: −0.58, 95% CI: −1.00 to −0.17), sperm vitality (SMD: −0.83, 95% CI: −1.11 to −0.54), circulating follicle-stimulating hormone (SMD: −0.87, 95% CI: −1.53 to −0.21), testosterone (SMD: −5.61, 95% CI: −10.90 to −0.31), and inhibin B (SMD: −2.42, 95% CI: −4.52 to −0.32), and a statistically significant increase of sperm DNA fragmentation (SMD: 0.76, 95% CI: 0.45 to 1.06) and mitochondrial membrane potential (SMD: 0.89, 95% CI: 0.49 to 1.28). No significant difference was found in semen volume, sperm total motility, circulating luteinizing hormone (LH), estradiol, prolactin and anti-Müllerian hormone (AMH) (P > 0.05). In conclusion, this meta-analysis demonstrated the effects of MetS on almost all the semen parameters and part of the circulating sex hormones, and MetS tended to be a risk factor for male infertility. Further larger-scale prospective designed studies were needed to confirm our findings.

Metabolic Syndrome and Reproduction

“…In conclusion, while several clinical and preclinical studies strongly support an association between MetS and hypogonadism [ 29 , 35 , 36 , 37 , 38 , 127 ], contrasting results have been reported on the relationship between MetS and semen parameters, and available studies used heterogeneous MetS definitions and investigated heterogeneous populations. So far, only one meta-analysis [ 70 ] has evaluated this topic, reporting a negative association between MetS and sperm parameters; however, advocating larger prospective investigations. Preclinical studies (meta-analyzed in [ 89 ]) were essentially in line with the clinical ones.…”

“…So far, only one meta-analysis [ 70 ] has assessed the effect of MetS on semen quality as well as on circulating sex hormones. The authors [ 70 ] analyzed eleven studies, with a total of 1.731 MetS cases and 11.740 controls.…”

“…So far, only one meta-analysis [ 70 ] has assessed the effect of MetS on semen quality as well as on circulating sex hormones. The authors [ 70 ] analyzed eleven studies, with a total of 1.731 MetS cases and 11.740 controls. Compared with controls, MetS cases had a statistically significant decrease of sperm concentration, total count, progressive motility, normal morphology, and vitality, along with an increase of sperm DNA fragmentation and abnormal mitochondrial membrane potential ( Figure 2 ).…”

“… Summary of the Zhao and Pang [ 70 ] meta-analysis on the effects of metabolic syndrome (MetS) on semen parameters. MMP, mitochondrial membrane potential.…”

Improvement Effect of Metformin on Female and Male Reproduction in Endocrine Pathologies and Its Mechanisms

“…A recent meta-analysis of 11 clinical studies involving 1731 men with MetS showed a significant decrease in total sperm count, sperm concentration, sperm survival, and the number of sperm with normal morphology and progressive motility, as well as an increase in sperm DNA fragmentation and functional changes in the mitochondrial energy and biogenesis [ 426 ]. Along with an androgen deficiency, the blood levels of FSH and inhibin B were significantly decreased in men with MetS, while the blood levels of LH, estrogen, and AMH were changed to a small extent [ 426 ].…”